1. Field of Invention
The present invention relates to the field of nautical safety devices. More particularly, the present invention relates to a device for providing emergency transit between a marine vessel and the surrounding water. More particularly yet, the present invention involves a modular, foldable ladder, where the ladder is portable and stowable aboard the vessel and deployable over a side of the vessel to provide safe transit between the water and the deck of the vessel.
2. Description of Prior Art
Throughout the long history of marine vessels, there have been the inherent hazards of water. For numerous reasons, it has been and continues to be necessary to provide some means by which an individual may both safely enter the water from a deck of a vessel and safely access the deck of the vessel from the water. Accordingly, various designs of ladder structures are found throughout the art of nautical devices. Many such designs are permanently mounted along the periphery of the vessel, typically supported by some portion of the vessel's hull. These types of ladder structures may be pivotally or statically mounted. Alternatively, many such ladder structures are removably mountable along the vessel's periphery. It is within this removably mountable category of ladder structure that the present invention resides.
In the field of nautical safety devices, there have been attempts, with varying degrees of success, to facilitate transit between the deck of a vessel and the water surrounding the vessel by providing a removably mounted ladder structure. In general, the complexity of such efforts has undercut whatever advantages they might otherwise offer during both emergency and non-emergency situations. Indeed, during typical nautical emergencies the time and effort involved in deploying and using complex and inefficient ladders is self-defeating. Typical non-folding ladders that are not welded, or otherwise fixed, to the vessel are usually cumbersome, heavy, and not readily stowable. Deployment of such prior-art ladders is difficult at best for one person working alone and valuable time is lost during emergency situations when a cumbersome or complex ladder is deployed. Some prior-art ladders even pose a hazard themselves when deployed because they are shaped and/or mounted in such a way that causes its elements to catch, foul, or snare lines or pier structures. Other prior-art nautical ladder structures have their own disadvantages.
One related prior-art nautical ladder is that of Lang (U.S. Pat. No. 3,892,290), which has two-piece and three-piece foldable configurations. In both configurations, there is included a set of parallel rails that have end-hooks latchable onto corresponding mounts along a side of a boat. Deployment of the Lang ladder involves holding it in a precarious position near the side of the boat so that it can be attached to the mounts. This deployment technique makes the risk of losing the ladder into the water high. As well, Lang fails to provide any rails or guides to assist anyone using the ladder. While a guide-chain is provided in one configuration, this is far from an ideal grasping element for assistance. Typically, chains pinch fingers and thus present the danger of a user losing his grip while on the ladder. Accordingly, Lang fails to provide a safe nautical ladder.
Other nautical ladders exist that are deficient for the same reasons noted in regard to the Lang device. A general defect of prior-art nautical ladders is that they are not suitable for emergency situations where medium to large vessels are concerned. Indeed, prior-art nautical ladders of the removably mounted type are typically designed for use in small recreational boats. Mounting such nautical ladders on a large vessel--such as a ferry--where the deck is much farther from the water becomes difficult to impossible. This is because the requisite length of ladder typically precludes stowability aboard boats. Even telescoping or otherwise extendable designs found in the prior-art do not provide adequate or safe transit between a deck and the water. Due to wave swells and the fixed height of the sides of the boat, the distance between the deck and the water can range from four up to eight feet or more. Concurrent with the development of the prior-art nautical ladders described above, other ladders have been developed with the goal of quickly facilitating transit between water and a boat. Four representative prior-art devices are those of Ritten (U.S. Pat. No. 4,724,925), Baranowski (U.S. Pat. No. 4,538,314), Sell (U.S. Pat. No. 3,794,140), and Thornburg et al. (U.S. Pat. No. 3,195,680).
The Ritten device is a nautical ladder having a ladder section and a mount section. The mount section has a step unit and a mount unit. The step unit is a pair of tubular siderails that carry flat tread steps. The mount unit is a pair of spaced-apart, tubular sections rotatably connected to the step unit. Mounting members, into which such tubular sections fit, permit the ladder to be mounted on a topside surface of a boat while supporting the ladder in its operating orientation. Ritten exhibits several flaws, including, most importantly, a lack of any guides or railings to assist a user. Further, aside from the small tread steps, Ritten does not provide any platform near water-level that would be a suitable landing for exhausted or injured individuals, as would be needed during emergency rescue situations. Yet further, the rigid ladder section of Ritten is neither compact for better stowability nor extendable for use on a large boat such as a ferry. Accordingly, Ritten fails to provide a nautical ladder that is both suitably safe and quick to set up during emergency situations on a large boat.
Baranowski includes a nautical boarding ramp similar to Ritten but having adjustable features that make it foldable. While the ramp of Baranowski also provides a landing platform, it does not provide sufficient extendibility to the water surface such as is needed for use on large boats with decks high above the water. Also, no safety rails or guides are shown for use with the ramp. Indeed, due to its cumbersome design, the ramp itself may be easily dropped overboard when a user attempts to hook it to the side of the boat. Therefore, Baranowski is not suitable for emergencies on large boats where safety and speedy setup are required.
Sell includes a boat ladder similar to the prior-art mentioned above but one that has guide rails. While a landing platform is shown as a component of the Sell device, it is located at boat-deck level and only one step is provided therebelow for access to and from the water. Although this design is suitable for recreational use on a small boat, it fails to provide a suitable transit between the water and a large boat. As well, Sell suffers from the deficiency seen throughout the prior-art, the absence of deployment means that is safe for both the rescuer and the rescued with minimal risk of dropping the ladder overboard.
Similar to the device of Sell, the boarding platform of Thornburg at al. includes a boat ladder for a small watercraft having a platform landing at deck-level and a foldable step therebeneath. Thornburg et al. does not, however, provide any guides or rails. Again, although this design is suitable for recreational use on a small boat, it fails to provide suitable transit between the water and a large boat during emergencies. Thornburg at al. suffers from the deficiency pervasive throughout the prior-art: the absence of quick, easy, and safe deployment with reduced risk of losing the ladder overboard.
Accordingly, the prior art fails to provide any nautical ladders suitable for quick and safe assembly and use--especially in emergency situations. Therefore, what is needed is a nautical ladder that is truly suitable for emergency use. What is also needed is such a device that is lightweight, portable, and of sturdy design. Further, what is needed is such a device that enables fast and safe utilization with a large boat, such as a ferry. Still further, what is needed is such a device that is readily deployable by a sole deckhand with minimal risk of dropping or otherwise losing the device overboard. What is also needed is that the nautical ladder system be mounted in such a way so as to eliminate any protrudances that can catch, foul, or snare lines or pier structures. Also, what is needed is such a nautical ladder system that is both foldable and compact so as to provide easy stowing.